1. Field of the Invention
The present invention relates to triorganosiloxydiphenylsilanols, which are novel organosilicone compounds useful as plasticizers for silicone rubbers. The present invention also relates to a method for the preparation of said triorganosiloxydiphenylsilanol and to a method for preparing filled organosiloxane compositions using these compounds.
2. Background Information
Silicone rubbers are used in a variety of applications because of their high resistance to heat and cold. Various types of inorganic fillers are typically blended into the polyorganosiloxanes present in the curable compositions used to prepare these rubbers to improve the physical properties of the cured rubber. However, as a result of a pseudo-crosslinking that results from interactions between the polyorganosiloxane and the inorganic filler, the blendability or workability during blending of the silicone rubber composition deteriorates with the passage of time In order to prevent this pseudo-crosslinking, curable organosiloxane compositions have heretofore been prepared using a silanol-containing low molecular weight organosilicon compound as a plasticizer for the silicone rubber. Examples of these plasticizers include but are not limited to diphenylsilanediol and oligomeric organosiloxanes such as alpha,omega-dihydroxydimethylsiloxanes alpha,omega-dihydroxymethylvinylsiloxanes, and alpha,omega-dihydroxymethylphenylsiloxanes.
The oligomeric organosiloxanes have not performed satisfactorily as silicone rubber plasticizers. Diphenylsilanediol performs well as a plasticizer, however its use is associated with the development of white spots on the surface of the cured silicone rubber.
The present inventors developed the present invention as the result of extensive research directed at solving the aforementioned problems associated with prior art plasticizers in curable organosiloxane compositions.